Feasibility of Nb3Sn in a μ-SMES concept

Today´s SMES related efforts are mainly concentrating on a number of small-scale devices for high value applications such as improving power quality and providing frequency control or dynamic response. The commercialised SMES units utilise NbTi at 4.2 K as a coil material. In addition some demonstration concepts have been tested with HTS materials operating at 20-30 K or even at 77 K. One approach is to utilise Nb₃Sn in the vicinity of 10 K. This kind of system has been constructed. The designed SMES coil is compared to a NbTi coil cooled with liquid helium and a conduction cooled BSCCO coil operating at 20 K. The starting point is a 200 kJ magnet where the coil volume has been optimised under electromagnetic and mechanical constraints. The comparison of these three coil concepts is mainly concentrated on the questions of stability and coil protection. The benefits and disadvantages of adopting Nb₃Sn as a coil material are emphasized